Electrical induction apparatus



May 3, 1933- v. M. MONTSINGE 2,116,404

ELECTR I CAL INDUCTION AP PARTUS File-d March 23, 193'? bg M L HisAbborneg.

Patented May' 3, 1938 PATENT oFFicE 2,116,404 ELEc'rnlcAL nvnUo'rloNAPPARATUS Vincent M. Montainger, Pittsfield, Mass., assigner to GeneralElectric Company, a corporation of New York Application March 2 3, 1937,serial No. 132,528 s claims. (c1. 11s-362) I'he invention relates toelectrical induction apparatus, such as a transformer or reactor,wherein a winding leg of a magnetic core is surrounded by a winding orwindings. The invention is furthermore particularly concerned withapparatus having high voltage windings of the disk coil type. Such ahigh voltage winding must be effectively insulated from the winding legof the core and from any low voltage winding which it may surround, andsuitable provision must be made for dissipating heat from the winding toprevent ex- 'y cessive temperatures. The necessary insulation is usuallyprovided by one or more insulating cylinders between the high voltagewindings and the winding leg of the magnetic core. The disk-coils iforming the high voltage winding are usually spaced from each other andfrom the insulating cylinder which they surround to provide passagewaysfor an insulating and cooling liquid in whichv theapparatus is immersed.It has been found that if the voltage of the winding in such anarrangement is increased to the point of breakdown,

corona will rst appear and breakdown will first take place along theinner edges of thedisk coils D where they are spaced a short distancefrom the insulating cylinder.

The general object of the invention is to provide an improvedarrangement of high voltage winding with its insulating cylinder whereina '30 much higher voltage is necessary before corona and breakdown willoccur.

The invention will be better `understood from the following descriptiontaken in connection with the accompanying drawing in which Fig. 1 is asimple partially diagrammatic view of a core type transformer havingwindings which may be arranged in accordance with the invention; Fig. 2is an enlarged view of a portion of the transformer, the windings inthis view being shown 40 partly in section; Fig. 3 is a sectional viewon the line 2 3 of F18. 2: Fig. 4 shows a detail'on the.

line 4-4- of Fig. 2. and Fig. 5 shows a modified form of the invention.Y

,Like'reference characters indicate similar parts 45 of thediiferentfigures of the drawing.

' The transformer shown in the drawing includes a magnetic core ilhaving two winding legs il y surroundedby high voltage windings I2 andlow voltage windings-i2, each low voltage winding I2 so being next toits winding leg Il and surrounded by its high voltagewinding I2. Eachhigh-voltage winding i2 is insulated from its low voltage winding il bytwo concentric insulating cylinders Il and Il which are spaced from eachother to prou lvide a duct or passageway It for a cooling liquid.

'Ihe' insulating cylinders Il ,and i5 are imperiorate and are formedwith end flanges il and il respectively which provide insulation betweenthe ends of the winding and the adjacent yokes` I9" of the magneticcore. Suitable spacing strips are provided between the insulatingcylinders i4 and I5 and between their flanges i'l and il.

In accordance with the inventionv the high voltage winding I2 includes.a plurality of spaced disk coils 2| with their inner Iedges in contactwith the outer surface of the insulating cylinder i4 which theysurround. There is thus no space for cooling liquid between thesediskcoils 2| and their insulating cylinder il so that if any corona 'startsat all it must startin the solid insulating material of the insulatingcylinder Il instead of in an insulating liquid and it is well known thatcorona will start much more easily in' liquid insulation than in solidinsulation. It is, however, not necessary that'the disk coils 2| fit sotightly against the insulating cylinder Il -as to exclude all liquidbecause the dielectric strength of a thin illm of insulating liquid ismuch higher in`proportion to its thickness than is that of a thickerlayer of such liquid.

The disk coils 2i are maintained in spaced relation by U-shaped spacers22 and simple spacing strips 23. The winding I2 must of 'course beheldin placeunder considerable pressure and it is therefore necessarythat the spacers 22 and 23 be held in alinement to avoid distortion ofthe individual coils 2|. To assure such alinement of the spacers 22 and23, the insulating cylinder I4 is formed with longitudinal grooves 24 inits outer surface and the inner ends of the spacers extend and fit intothese grooves. The spacers 22 extend along opposite faces of the coils2| and around the inner edges where they iit into the grooves 2l. Thespacing strips 23 are disposed between the U-shaped spacers 22 and theirinner ends also extend into the grooves 24. The spacing strips 22 may ofcourse be of any desired thickness depending upon the desired spacing ofthe coils 2i or they may be omitted if not needed.

The insulating liquid in which the transformer may be immersed will havefree access to the upper and lower faces and to the outer edges'ofeachof the coils 2l so as to absorb heat from these coils to improve thecirculation of the liquid. To improve the circulation of the liquid sothat it may carry away the heat more rapidly, alternate coils are formedin two concentric spaced portions so that ducts 2l extend between theupper and lower surfaces of these alternate coils. The cooling liquidmay thus flow surfaces of those coils which are provided with the ducts25 but also along the surfaces of the other coils not so provided withducts and which are therefore solid, and thus the heat is dissipatedeffectively from all of the coils even though the cooling liquid issubstantially ex-I, eluded from the inner edges of the coils next to thei:ieriiisula'ting cylinder upon which they are suppor In the modifiedform of the invention shown in Fig. 5, alternate solid coils are wound.tightly over the insulating cylinder il and with -their inner edges incontact therewith -The ducts 2l associated with the other coils,however, are provided by. spacing the inner edges of the other coilsfrom the cylinder il instead of forming these ducts through these coilsnear their inner edges. 'I'he spacing of the inner edges of alternatecoils from the cylinder Il to provide the ducts ZI is permissiblebecause of the i'act'that the adjacent coils are in contact with theinsulating cylinder and definitely establish the potential distributionalong the cylinder` at .frequent intervals so that the voltage acrossthe ducts 25 will not be sufilcient to produce corona.

'I'he invention has been explained by describing and illustrating aparticular transformer constructed in accordance therewith, but it willbe apparent that changes may be made without departing from the spiritof the invention and the scope of the appended claims.

' insulating vcylinder with longitudinal grooves in its outer surface,and spaced disk coils surrounding said cylinder with their inner edgesin contact with the cylinder, alternate coils having y ducts near theirinner edges, and the other coils being solid.

3. Electrical induction apparatus including an insulating cylinder withlongitudinal grooves in its outer surface, spaced disk coils surroundingsaid cylinder with their inner edges in contact with the cylinder, andspacers between said coils and extending into said grooves, alternatecoils having ducts near their inner edges, and the other coils beingsolid.

4. Electrical induction apparatus including an imperforate insulatingcylinder, a plurality of spaced disk coils, alternate coils being solidand each having an edge in contact with the cylinder. there being a ductassociated with each ofthe other coils and connecting the adjacentspaces near saidcylinder.

5. Electrical induction apparatus including an imperforate insulatingcylinder, a plurality of spaced disk coils surrounding said cylinder,alternate coils being solid and each having its inner edge in contactwith the cylinder, there being a duct associated with each of the othercoils and connecting the adjacent spaces near said cylinder.

VINCENT M. MONTBINGER.

